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Wang Y, Zhang Y, Cui Q, Feng Y, Xuan J. Composition of Lignocellulose Hydrolysate in Different Biorefinery Strategies: Nutrients and Inhibitors. Molecules 2024; 29:2275. [PMID: 38792135 PMCID: PMC11123716 DOI: 10.3390/molecules29102275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Revised: 05/06/2024] [Accepted: 05/09/2024] [Indexed: 05/26/2024] Open
Abstract
The hydrolysis and biotransformation of lignocellulose, i.e., biorefinery, can provide human beings with biofuels, bio-based chemicals, and materials, and is an important technology to solve the fossil energy crisis and promote global sustainable development. Biorefinery involves steps such as pretreatment, saccharification, and fermentation, and researchers have developed a variety of biorefinery strategies to optimize the process and reduce process costs in recent years. Lignocellulosic hydrolysates are platforms that connect the saccharification process and downstream fermentation. The hydrolysate composition is closely related to biomass raw materials, the pretreatment process, and the choice of biorefining strategies, and provides not only nutrients but also possible inhibitors for downstream fermentation. In this review, we summarized the effects of each stage of lignocellulosic biorefinery on nutrients and possible inhibitors, analyzed the huge differences in nutrient retention and inhibitor generation among various biorefinery strategies, and emphasized that all steps in lignocellulose biorefinery need to be considered comprehensively to achieve maximum nutrient retention and optimal control of inhibitors at low cost, to provide a reference for the development of biomass energy and chemicals.
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Affiliation(s)
- Yilan Wang
- Department of Bioscience and Bioengineering, School of Chemistry and Biological Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Beijing 100083, China
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101, China
| | - Yuedong Zhang
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101, China
- Shandong Energy Institute, 189 Songling Road, Qingdao 266101, China
- Qingdao New Energy Shandong Laboratory, 189 Songling Road, Qingdao 266101, China
| | - Qiu Cui
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101, China
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, China
| | - Yingang Feng
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101, China
- Shandong Energy Institute, 189 Songling Road, Qingdao 266101, China
- Qingdao New Energy Shandong Laboratory, 189 Songling Road, Qingdao 266101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jinsong Xuan
- Department of Bioscience and Bioengineering, School of Chemistry and Biological Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Beijing 100083, China
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Azhar S, Aihetasham A, Chaudhary A, Hussain Z, Abdul Rehman R, Abbas G, Alharbi SA, Ansari MJ, Qamer S. Cellulolytic and Ethanologenic Evaluation of Heterotermes indicola's Gut-Associated Bacterial Isolates. ACS OMEGA 2024; 9:12084-12100. [PMID: 38496968 PMCID: PMC10938596 DOI: 10.1021/acsomega.3c10030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 02/09/2024] [Accepted: 02/19/2024] [Indexed: 03/19/2024]
Abstract
Cellulose is the basic component of lignocellulosic biomass (LCB) making it a suitable substrate for bioethanol fermentation. Cellulolytic and ethanologenic bacteria possess cellulases that convert cellulose to glucose, which in turn yields ethanol subsequently. Heterotermes indicola is a subterranean termite that causes destructive damage by consuming wooden structures of infrastructure, LCB products, etc. Prospectively, the study envisioned the screening of cellulolytic and ethanologenic bacteria from the termite gut. Twenty six bacterial strains (H1-H26) based on varied colonial morphologies were isolated. Bacterial cellulolytic activity was tested biochemically. Marked gas production in the form of bubbles (0.1-4 cm) in Durham tubes was observed in H3, H7, H13, H15, H17, H21, and H22. Sugar degradation of all isolates was indicated by pink to maroon color development with the tetrazolium salt. Hallow zones (0.42-11 mm) by Congo red staining was exhibited by all strains except H2, H7, H8, and H19. Among the 26 bacterial isolates, 12 strains were identified as efficient cellulolytic bacteria. CMCase activity and ethanol titer of all isolates varied from 1.30 ± 0.03 (H13) to 1.83 ± 0.01 (H21) umol/mL/min and 2.36 ± 0.01 (H25) to 7.00 ± 0.01 (H21) g/L, respectively. Likewise, isolate H21 exhibited an ethanol yield of 0.40 ± 0.10 g/g with 78.38 ± 2.05% fermentation efficiency. Molecular characterization of four strains, Staphylococcus sp. H13, Acinetobacter baumanni H17, Acinetobacter sp. H21, and Acinetobacter nosocomialis H22, were based on the maximum cellulolytic index and the ethanol yield. H. indicola harbor promising and novel bacteria with a natural cellulolytic tendency for efficient bioconversion of LCB to value-added products. Hence, the selected cellulolytic bacteria can become an excellent addition for use in enzyme purification, composting, and production of biofuel at large.
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Affiliation(s)
- Sana Azhar
- Institute
of Zoology, University of the Punjab, Lahore 54590, Pakistan
| | - Ayesha Aihetasham
- Institute
of Zoology, University of the Punjab, Lahore 54590, Pakistan
| | - Asma Chaudhary
- Department
of Zoology, Division of Science and Technology, University of Education, Township, Lahore54770, Pakistan
| | - Zawar Hussain
- Department
of Zoology, Division of Science and Technology, University of Education, Township, Lahore54770, Pakistan
| | - Rahat Abdul Rehman
- Department
of Forensic Medicine, University of Health
Sciences, Lahore54600, Pakistan
| | - Ghulam Abbas
- Department
of Biotechnology, University of Agriculture, Dera Ismail Khan, KPK 29111, Pakistan
| | - Sulaiman Ali Alharbi
- Department
of Botany and Microbiology, College of Science, King Saud University, PO Box-2455, Riyadh 11451, Kingdom of Saudi Arabia
| | - Mohammad Javed Ansari
- Department
of Botany, Hindu College, Moradabad (Mahatma
Jyotiba Phule Rohilkhand University), Bareilly, Uttar Pradesh 243001, India
| | - Samina Qamer
- Department
of Zoology, Rawalpindi Women University, Satellite Town, Rawalpindi 46300, Pakistan
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3
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Yue S, Zhang M. Global trends and future prospects of lactic acid production from lignocellulosic biomass. RSC Adv 2023; 13:32699-32712. [PMID: 37942446 PMCID: PMC10628742 DOI: 10.1039/d3ra06577d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Accepted: 10/24/2023] [Indexed: 11/10/2023] Open
Abstract
Lignocellulosic biomass (LCB) stands as a substantial and sustainable resource capable of addressing energy and environmental challenges. This study employs bibliometric analysis to investigate research trends in lactic acid (LA) production from LCB spanning the years 1991 to 2022. The analysis reveals a consistent growth trajectory with minor fluctuations in LA production from LCB. Notably, there's a significant upswing in publications since 2009. Bioresource Technology and Applied Microbiology and Biotechnology emerge as the top two journals with extensive contributions in the realm of LA production from LCB. China takes a prominent position in this research domain, boasting the highest total publication count (736), betweenness centrality value (0.30), and the number of collaborating countries (42), surpassing the USA and Japan by a considerable margin. The author keywords analysis provides valuable insights into the core themes in LA production from LCB. Furthermore, co-citation reference analysis delineates four principal domains related to LA production from LCB, with three associated with microbial conversion and one focused on chemical catalytic conversion. Additionally, this study examines commonly used LCB, microbial LA producers, and compares microbial fermentation to chemical catalytic conversion for LCB-based LA production, providing comprehensive insights into the current state of this field and suggesting future research directions.
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Affiliation(s)
- Siyuan Yue
- Laboratory of Soil and Environmental Microbiology, Division of Systems Bioengineering, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School of Bioresources and Bioenvironmental Sciences, Kyushu University Fukuoka 819-0395 Japan
- Institute of Microbiology, Jiangxi Academy of Sciences Nanchang Jiangxi Province 330096 China
| | - Min Zhang
- Laboratory of Soil and Environmental Microbiology, Division of Systems Bioengineering, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School of Bioresources and Bioenvironmental Sciences, Kyushu University Fukuoka 819-0395 Japan
- Jiangxi Copper Technology Research Institute, Jiangxi Copper Corporation Nanchang Jiangxi Province 330096 China
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Application of Bioelectrochemical Systems and Anaerobic Additives in Wastewater Treatment: A Conceptual Review. Int J Mol Sci 2023; 24:ijms24054753. [PMID: 36902185 PMCID: PMC10003464 DOI: 10.3390/ijms24054753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 02/25/2023] [Accepted: 02/28/2023] [Indexed: 03/06/2023] Open
Abstract
The interspecies electron transfer (IET) between microbes and archaea is the key to how the anaerobic digestion process performs. However, renewable energy technology that utilizes the application of a bioelectrochemical system together with anaerobic additives such as magnetite-nanoparticles can promote both direct interspecies electron transfer (DIET) as well as indirect interspecies electron transfer (IIET). This has several advantages, including higher removal of toxic pollutants present in municipal wastewater, higher biomass to renewable energy conversion, and greater electrochemical efficiencies. This review explores the synergistic influence of bioelectrochemical systems and anaerobic additives on the anaerobic digestion of complex substrates such as sewage sludge. The review discussions present the mechanisms and limitations of the conventional anaerobic digestion process. In addition, the applicability of additives in syntrophic, metabolic, catalytic, enzymatic, and cation exchange activities of the anaerobic digestion process are highlighted. The synergistic effect of bio-additives and operational factors of the bioelectrochemical system is explored. It is elucidated that a bioelectrochemical system coupled with nanomaterial additives can increase biogas-methane potential compared to anaerobic digestion. Therefore, the prospects of a bioelectrochemical system for wastewater require research attention.
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Synergy of Cellulase Systems between Acetivibrio thermocellus and Thermoclostridium stercorarium in Consolidated-Bioprocessing for Cellulosic Ethanol. Microorganisms 2022; 10:microorganisms10030502. [PMID: 35336078 PMCID: PMC8951355 DOI: 10.3390/microorganisms10030502] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 02/21/2022] [Accepted: 02/21/2022] [Indexed: 11/18/2022] Open
Abstract
Anaerobes harbor some of the most efficient biological machinery for cellulose degradation, especially thermophilic bacteria, such as Acetivibrio thermocellus and Thermoclostridium stercorarium, which play a fundamental role in transferring lignocellulose into ethanol through consolidated bioprocessing (CBP). In this study, we compared activities of two cellulase systems under varying kinds of hemicellulose and cellulose. A. thermocellus was identified to contribute specifically to cellulose hydrolysis, whereas T. stercorarium contributes to hemicellulose hydrolysis. The two systems were assayed in various combinations to assess their synergistic effects using cellulose and corn stover as the substrates. Their maximum synergy degrees on cellulose and corn stover were, respectively, 1.26 and 1.87 at the ratio of 3:2. Furthermore, co-culture of these anaerobes on the mixture of cellulose and xylan increased ethanol concentration from 21.0 to 40.4 mM with a high cellulose/xylan-to-ethanol conversion rate of up to 20.7%, while the conversion rates of T. stercorarium and A. thermocellus monocultures were 19.3% and 15.2%. The reason is that A. thermocellus had the ability to rapidly degrade cellulose while T. stercorarium co-utilized both pentose and hexose, the metabolites of cellulose degradation, to produce ethanol. The synergistic effect of cellulase systems and metabolic pathways in A. thermocellus and T. stercorarium provides a novel strategy for the design, selection, and optimization of ethanol production from cellulosic biomass through CBP.
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Bacterial valorization of pulp and paper industry process streams and waste. Appl Microbiol Biotechnol 2021; 105:1345-1363. [PMID: 33481067 DOI: 10.1007/s00253-021-11107-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 12/28/2020] [Accepted: 01/08/2021] [Indexed: 10/22/2022]
Abstract
The pulp and paper industry is a major source of lignocellulose-containing streams. The components of lignocellulose material are lignin, hemicellulose, and cellulose that may be hydrolyzed into their smaller components and used as feedstocks for valorization efforts. Much of this material is contained in underutilized streams and waste products, such as black liquor, pulp and paper sludge, and wastewater. Bacterial fermentation strategies have suitable potential to upgrade lignocellulosic biomass contained in these streams to value-added chemicals. Bacterial conversion allows for a sustainable and economically feasible approach to valorizing these streams, which can bolster and expand applications of the pulp and paper industry. This review discusses the composition of pulp and paper streams, bacterial isolates from process streams that can be used for lignocellulose biotransformations, and technological approaches for improving valorization efforts. KEY POINTS: • Reviews the conversion of pulp and paper industry waste by bacterial isolates. • Metabolic pathways for the breakdown of lignocellulose components. • Methods for isolating bacteria, determining value-added products, and increasing product yields.
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Yoav S, Stern J, Salama-Alber O, Frolow F, Anbar M, Karpol A, Hadar Y, Morag E, Bayer EA. Directed Evolution of Clostridium thermocellum β-Glucosidase A Towards Enhanced Thermostability. Int J Mol Sci 2019; 20:E4701. [PMID: 31547488 PMCID: PMC6801902 DOI: 10.3390/ijms20194701] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 09/19/2019] [Accepted: 09/20/2019] [Indexed: 12/27/2022] Open
Abstract
β-Glucosidases are key enzymes in the process of cellulose utilization. It is the last enzyme in the cellulose hydrolysis chain, which converts cellobiose to glucose. Since cellobiose is known to have a feedback inhibitory effect on a variety of cellulases, β-glucosidase can prevent this inhibition by hydrolyzing cellobiose to non-inhibitory glucose. While the optimal temperature of the Clostridium thermocellum cellulosome is 70 °C, C. thermocellum β-glucosidase A is almost inactive at such high temperatures. Thus, in the current study, a random mutagenesis directed evolutionary approach was conducted to produce a thermostable mutant with Kcat and Km, similar to those of the wild-type enzyme. The resultant mutant contained two mutations, A17S and K268N, but only the former was found to affect thermostability, whereby the inflection temperature (Ti) was increased by 6.4 °C. A17 is located near the central cavity of the native enzyme. Interestingly, multiple alignments revealed that position 17 is relatively conserved, whereby alanine is replaced only by serine. Upon the addition of the thermostable mutant to the C. thermocellum secretome for subsequent hydrolysis of microcrystalline cellulose at 70 °C, a higher soluble glucose yield (243%) was obtained compared to the activity of the secretome supplemented with the wild-type enzyme.
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Affiliation(s)
- Shahar Yoav
- Department of Plant Pathology and Microbiology, Robert H. Smith Faculty of Agriculture, Food and Environment, the Advanced School for Environmental Studies, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 7610001, Israel.
| | - Johanna Stern
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 7610001, Israel.
| | - Orly Salama-Alber
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 7610001, Israel.
| | - Felix Frolow
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Tel Aviv 6997801, Israel.
| | - Michael Anbar
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 7610001, Israel.
| | - Alon Karpol
- CelDezyner, 2 Bergman St, Tamar Science Park, Rehovot 7670504, Israel.
| | - Yitzhak Hadar
- Department of Plant Pathology and Microbiology, Robert H. Smith Faculty of Agriculture, Food and Environment, the Advanced School for Environmental Studies, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
| | - Ely Morag
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 7610001, Israel.
| | - Edward A Bayer
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 7610001, Israel.
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Wang Y, Leng L, Islam MK, Liu F, Lin CSK, Leu SY. Substrate-Related Factors Affecting Cellulosome-Induced Hydrolysis for Lignocellulose Valorization. Int J Mol Sci 2019; 20:ijms20133354. [PMID: 31288425 PMCID: PMC6651384 DOI: 10.3390/ijms20133354] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 06/30/2019] [Accepted: 07/03/2019] [Indexed: 11/22/2022] Open
Abstract
Cellulosomes are an extracellular supramolecular multienzyme complex that can efficiently degrade cellulose and hemicelluloses in plant cell walls. The structural and unique subunit arrangement of cellulosomes can promote its adhesion to the insoluble substrates, thus providing individual microbial cells with a direct competence in the utilization of cellulosic biomass. Significant progress has been achieved in revealing the structures and functions of cellulosomes, but a knowledge gap still exists in understanding the interaction between cellulosome and lignocellulosic substrate for those derived from biorefinery pretreatment of agricultural crops. The cellulosomic saccharification of lignocellulose is affected by various substrate-related physical and chemical factors, including native (untreated) wood lignin content, the extent of lignin and xylan removal by pretreatment, lignin structure, substrate size, and of course substrate pore surface area or substrate accessibility to cellulose. Herein, we summarize the cellulosome structure, substrate-related factors, and regulatory mechanisms in the host cells. We discuss the latest advances in specific strategies of cellulosome-induced hydrolysis, which can function in the reaction kinetics and the overall progress of biorefineries based on lignocellulosic feedstocks.
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Affiliation(s)
- Ying Wang
- Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Guangdong Institute of Eco-Environmental Science & Technology, Guangzhou 510650, China
- Department of Civil and Environmental Engineering, the Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China
| | - Ling Leng
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 6, Higashi 1-1-1, Tsukuba, Ibaraki 305-8566, Japan
| | - Md Khairul Islam
- Department of Civil and Environmental Engineering, the Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China
| | - Fanghua Liu
- Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Guangdong Institute of Eco-Environmental Science & Technology, Guangzhou 510650, China
| | - Carol Sze Ki Lin
- School of Energy and Environment, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR, China
| | - Shao-Yuan Leu
- Department of Civil and Environmental Engineering, the Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China.
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Liu S, Liu YJ, Feng Y, Li B, Cui Q. Construction of consolidated bio-saccharification biocatalyst and process optimization for highly efficient lignocellulose solubilization. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:35. [PMID: 30820245 PMCID: PMC6378752 DOI: 10.1186/s13068-019-1374-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 02/07/2019] [Indexed: 06/09/2023]
Abstract
BACKGROUND The industrial conversion of biomass to high-value biofuels and biochemical is mainly restricted by lignocellulose solubilization. Consolidated bio-saccharification (CBS) is considered a promising process for lignocellulose solubilization depending on whole-cell biocatalysts that simultaneously perform effective cellulase production and hydrolysis. However, it usually takes a long time to reach a high saccharification level using the current CBS biocatalyst and process. RESULTS To promote the saccharification efficiency and reduce the cost, a Clostridium thermocellum recombinant strain ∆pyrF::KBm was constructed as a new CBS biocatalyst in this study. The key CBS factors, including the medium, inoculum size and cultivation, and substrate load, were investigated and optimized. The saccharification process was also stimulated by adding free hemicellulases, suggesting the need to further enhance hemicellulase activity of the whole-cell catalyst. Under the optimal conditions, the CBS process was shortened by 50% with pretreated wheat straw as the substrate. The sugar yield reached 0.795 g/g and the saccharification level was 89.3%. CONCLUSIONS This work provided a new biocatalyst and an optimized process of CBS and confirmed that CBS is a feasible strategy for cost-efficient solubilization of lignocellulose, which will greatly promote the industrial utilization of lignocellulosic biomass.
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Affiliation(s)
- Shiyue Liu
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
- Dalian National Laboratory for Clean Energy, Chinese Academy of Sciences, Dalian, China
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Ya-Jun Liu
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
- Dalian National Laboratory for Clean Energy, Chinese Academy of Sciences, Dalian, China
| | - Yingang Feng
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
- Dalian National Laboratory for Clean Energy, Chinese Academy of Sciences, Dalian, China
| | - Bin Li
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
- Dalian National Laboratory for Clean Energy, Chinese Academy of Sciences, Dalian, China
| | - Qiu Cui
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
- Dalian National Laboratory for Clean Energy, Chinese Academy of Sciences, Dalian, China
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Ren Z, You W, Wu S, Poetsch A, Xu C. Secretomic analyses of Ruminiclostridium papyrosolvens reveal its enzymatic basis for lignocellulose degradation. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:183. [PMID: 31338125 PMCID: PMC6628489 DOI: 10.1186/s13068-019-1522-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 07/05/2019] [Indexed: 05/07/2023]
Abstract
BACKGROUND Efficient biotechnological conversion of lignocellulosic biomass to valuable products, such as transportation biofuels, is ecologically attractive, yet requires substantially improved mechanistic understanding and optimization to become economically feasible. Cellulolytic clostridia, such as Ruminiclostridium papyrosolvens (previously Clostridium papyrosolvens), produce a wide variety of carbohydrate-active enzymes (CAZymes) including extracellular multienzyme complexes-cellulosomes with different specificities for enhanced cellulosic biomass degradation. Identification of the secretory components, especially CAZymes, during bacterial growth on lignocellulose and their influence on bacterial catalytic capabilities provide insight into construction of potent cellulase systems of cell factories tuned or optimized for the targeted substrate by matching the type and abundance of enzymes and corresponding transporters. RESULTS In this study, we firstly predicted a total of 174 putative CAZymes from the genome of R. papyrosolvens, including 74 cellulosomal components. To explore profile of secreted proteins involved in lignocellulose degradation, we compared the secretomes of R. papyrosolvens grown on different substrates using label-free quantitative proteomics. CAZymes, extracellular solute-binding proteins (SBPs) of transport systems and proteins involved in spore formation were enriched in the secretome of corn stover for lignocellulose degradation. Furthermore, compared with free CAZymes, complex CAZymes (cellulosomal components) had larger fluctuations in variety and abundance of enzymes among four carbon sources. In particular, cellulosomal proteins encoded by the cip-cel operon and the xyl-doc gene cluster had the highest abundance with corn stover as substrate. Analysis of differential expression of CAZymes revealed a substrate-dependent secretion pattern of CAZymes, which was consistent with their catalytic activity from each secretome determined on different cellulosic substrates. The results suggest that the expression of CAZymes is regulated by the type of substrate in the growth medium. CONCLUSIONS In the present study, our results demonstrated the complexity of the lignocellulose degradation systems of R. papyrosolvens and showed the potency of its biomass degradation activity. Differential proteomic analyses and activity assays of CAZymes secreted by R. papyrosolvens suggested a distinct environment-sensing strategy for cellulose utilization in which R. papyrosolvens modulated the composition of the CAZymes, especially cellulosome, according to the degradation state of its natural substrate.
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Affiliation(s)
- Zhenxing Ren
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan, 030006 Shanxi China
- Institute of Applied Chemistry, Shanxi University, Taiyuan, 030006 Shanxi China
| | - Wuxin You
- Department of Plant Biochemistry, Ruhr University Bochum, 44801 Bochum, Germany
| | - Shasha Wu
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan, 030006 Shanxi China
| | - Ansgar Poetsch
- Department of Plant Biochemistry, Ruhr University Bochum, 44801 Bochum, Germany
- School of Biomedical and Healthcare Sciences, University of Plymouth, Plymouth, PL48AA UK
| | - Chenggang Xu
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan, 030006 Shanxi China
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11
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Chang JJ, Anandharaj M, Ho CY, Tsuge K, Tsai TY, Ke HM, Lin YJ, Ha Tran MD, Li WH, Huang CC. Biomimetic strategy for constructing Clostridium thermocellum cellulosomal operons in Bacillus subtilis. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:157. [PMID: 29930703 PMCID: PMC5991470 DOI: 10.1186/s13068-018-1151-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 05/23/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND Enzymatic conversion of lignocellulosic biomass into soluble sugars is a major bottleneck in the plant biomass utilization. Several anaerobic organisms cope these issues via multiple-enzyme complex system so called 'cellulosome'. Hence, we proposed a "biomimic operon" concept for making an artificial cellulosome which can be used as a promising tool for the expression of cellulosomal enzymes in Bacillus subtilis. RESULTS According to the proteomic analysis of Clostridium thermocellum ATCC27405 induced by Avicel or cellobiose, we selected eight highly expressed cellulosomal genes including a scaffoldin protein gene (cipA), a cell-surface anchor gene (sdbA), two exoglucanase genes (celK and celS), two endoglucanase genes (celA and celR), and two xylanase genes (xynC and xynZ). Arranging these eight genes in two different orders, we constructed two different polycistronic operons using the ordered gene assembly in Bacillus method. This is the first study to express the whole CipA along with cellulolytic enzymes in B. subtilis. Each operon was successfully expressed in B. subtilis RM125, and the protein complex assembly, cellulose-binding ability, thermostability, and cellulolytic activity were demonstrated. The operon with a higher xylanase activity showed greater saccharification on complex cellulosic substrates such as Napier grass than the other operon. CONCLUSIONS In this study, a strategy for constructing an efficient cellulosome system was developed and two different artificial cellulosomal operons were constructed. Both operons could efficiently express the cellulosomal enzymes and exhibited cellulose saccharification. This strategy can be applied to different industries with cellulose-containing materials, such as papermaking, biofuel, agricultural compost, mushroom cultivation, and waste processing industries.
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Affiliation(s)
- Jui-Jen Chang
- Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, 402 Taiwan
| | - Marimuthu Anandharaj
- Biodiversity Research Center, Academia Sinica, Taipei, 11529 Taiwan
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung Hsing University and Academia Sinica, Taipei, 11529 Taiwan
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 40227 Taiwan
| | - Cheng-Yu Ho
- Department of Life Sciences, National Chung Hsing University, Taichung, 40227 Taiwan
| | - Kenji Tsuge
- Institute for Advanced Biosciences, Keio University, 403-1 Nipponkoku, Daihoji, Tsuruoka, Yamagata 997-0017 Japan
| | - Tsung-Yu Tsai
- Biodiversity Research Center, Academia Sinica, Taipei, 11529 Taiwan
| | - Huei-Mien Ke
- Biodiversity Research Center, Academia Sinica, Taipei, 11529 Taiwan
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 40227 Taiwan
| | - Yu-Ju Lin
- Biodiversity Research Center, Academia Sinica, Taipei, 11529 Taiwan
| | - Minh Dung Ha Tran
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung Hsing University and Academia Sinica, Taipei, 11529 Taiwan
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 40227 Taiwan
- Department of Life Sciences, National Chung Hsing University, Taichung, 40227 Taiwan
| | - Wen-Hsiung Li
- Biodiversity Research Center, Academia Sinica, Taipei, 11529 Taiwan
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung Hsing University and Academia Sinica, Taipei, 11529 Taiwan
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 40227 Taiwan
- Biotechnology Center, National Chung Hsing University, Taichung, 40227 Taiwan
- Department of Ecology and Evolution, University of Chicago, Chicago, IL 60637 USA
| | - Chieh-Chen Huang
- Department of Life Sciences, National Chung Hsing University, Taichung, 40227 Taiwan
- Innovation and Development Center of Sustainable Agriculture, National Chung Hsing University, Taichung, 40227 Taiwan
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Stern J, Moraïs S, Ben-David Y, Salama R, Shamshoum M, Lamed R, Shoham Y, Bayer EA, Mizrahi I. Assembly of Synthetic Functional Cellulosomal Structures onto the Cell Surface of Lactobacillus plantarum, a Potent Member of the Gut Microbiome. Appl Environ Microbiol 2018; 84:e00282-18. [PMID: 29453253 PMCID: PMC5881048 DOI: 10.1128/aem.00282-18] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 02/08/2018] [Indexed: 12/27/2022] Open
Abstract
Heterologous display of enzymes on microbial cell surfaces is an extremely desirable approach, since it enables the engineered microbe to interact directly with the plant wall extracellular polysaccharide matrix. In recent years, attempts have been made to endow noncellulolytic microbes with genetically engineered cellulolytic capabilities for improved hydrolysis of lignocellulosic biomass and for advanced probiotics. Thus far, however, owing to the hurdles encountered in secreting and assembling large, intricate complexes on the bacterial cell wall, only free cellulases or relatively simple cellulosome assemblies have been introduced into live bacteria. Here, we employed the "adaptor scaffoldin" strategy to compensate for the low levels of protein displayed on the bacterial cell surface. That strategy mimics natural elaborated cellulosome architectures, thus exploiting the exponential features of their Lego-like combinatorics. Using this approach, we produced several bacterial consortia of Lactobacillus plantarum, a potent gut microbe which provides a very robust genetic framework for lignocellulosic degradation. We successfully engineered surface display of large, fully active self-assembling cellulosomal complexes containing an unprecedented number of catalytic subunits all produced in vivo by the cell consortia. Our results demonstrate that the enzyme stability and performance of the cellulosomal machinery, which are superior to those seen with the equivalent secreted free enzyme system, and the high cellulase-to-xylanase ratios proved beneficial for efficient degradation of wheat straw.IMPORTANCE The multiple benefits of lactic acid bacteria are well established in health and industry. Here we present an approach designed to extensively increase the cell surface display of proteins via successive assembly of interactive components. Our findings present a stepping stone toward proficient engineering of Lactobacillus plantarum, a widespread, environmentally important bacterium and potent microbiome member, for improved degradation of lignocellulosic biomass and advanced probiotics.
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Affiliation(s)
- Johanna Stern
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Sarah Moraïs
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
- Faculty of Natural Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Yonit Ben-David
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Rachel Salama
- Department of Biotechnology and Food Engineering, The Technion Israel Institute of Technology, Haifa, Israel
| | - Melina Shamshoum
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Raphael Lamed
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv, Israel
| | - Yuval Shoham
- Department of Biotechnology and Food Engineering, The Technion Israel Institute of Technology, Haifa, Israel
| | - Edward A Bayer
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Itzhak Mizrahi
- Faculty of Natural Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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13
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Liu H, Sun J, Chang JS, Shukla P. Engineering microbes for direct fermentation of cellulose to bioethanol. Crit Rev Biotechnol 2018; 38:1089-1105. [DOI: 10.1080/07388551.2018.1452891] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- Hao Liu
- State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, China
| | - Jianliang Sun
- State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, China
| | - Jo-Shu Chang
- Department of Chemical Engineering, National Cheng Kung University, Tainan, Taiwan, China
| | - Pratyoosh Shukla
- Enzyme Technology and Protein Bioinformatics Laboratory, Department of Microbiology, Maharshi Dayanand University, Rohtak, India
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Singh N, Mathur AS, Gupta RP, Barrow CJ, Tuli D, Puri M. Enhanced cellulosic ethanol production via consolidated bioprocessing by Clostridium thermocellum ATCC 31924☆. BIORESOURCE TECHNOLOGY 2018; 250:860-867. [PMID: 30001594 DOI: 10.1016/j.biortech.2017.11.048] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 11/14/2017] [Accepted: 11/15/2017] [Indexed: 05/23/2023]
Abstract
The production of bioethanol was studied by the cultivation of Clostridium thermocellum ATCC 31924 in MTC medium including crystalline cellulose as the sole substrate. The effects of key operational parameters that affect bioethanol production from microcrystalline cellulose were optimized. Under optimum conditions (pH 8.0, temperature 55 °C, inoculum size 4% (v/v) and 0.5% (w/v) substrate concentration), a maximum ethanol yield of 0.30 g ethanol/g cellulose consumed and 95.32% cellulose conversion was obtained. An inclusion of modest acetate concentration in the medium showed that carbon flux shifted away from lactate accompanied by 20% increase in ethanol production. It suggests that strain ATCC 31924 differed in its cellulose conversion efficacy and optimum pH requirements compared to the other reported strains of Clostridium thermocellum. The purified cellulosome of strain ATCC 31924 found to be rich in both cellulase and xylanase enzymes emphasizing the importance of this strain for the degradation of lignocellulosic biomass.
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Affiliation(s)
- Nisha Singh
- Centre for Chemistry and Biotechnology, Deakin University, Waurn Ponds, Geelong, Victoria 3216, Australia; DBT-IOC Centre for Advance Bioenergy Research, Research & Development Centre, Indian Oil Corporation Limited, Sector-13, Faridabad 121007, India
| | - Anshu S Mathur
- DBT-IOC Centre for Advance Bioenergy Research, Research & Development Centre, Indian Oil Corporation Limited, Sector-13, Faridabad 121007, India
| | - Ravi P Gupta
- DBT-IOC Centre for Advance Bioenergy Research, Research & Development Centre, Indian Oil Corporation Limited, Sector-13, Faridabad 121007, India
| | - Colin J Barrow
- Centre for Chemistry and Biotechnology, Deakin University, Waurn Ponds, Geelong, Victoria 3216, Australia
| | - Deepak Tuli
- DBT-IOC Centre for Advance Bioenergy Research, Research & Development Centre, Indian Oil Corporation Limited, Sector-13, Faridabad 121007, India
| | - Munish Puri
- Centre for Chemistry and Biotechnology, Deakin University, Waurn Ponds, Geelong, Victoria 3216, Australia.
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Osiro KO, de Camargo BR, Satomi R, Hamann PRV, Silva JP, de Sousa MV, Quirino BF, Aquino EN, Felix CR, Murad AM, Noronha EF. Characterization of Clostridium thermocellum (B8) secretome and purified cellulosomes for lignocellulosic biomass degradation. Enzyme Microb Technol 2017; 97:43-54. [DOI: 10.1016/j.enzmictec.2016.11.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2016] [Revised: 11/04/2016] [Accepted: 11/05/2016] [Indexed: 11/16/2022]
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16
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Ábrego U, Chen Z, Wan C. Consolidated Bioprocessing Systems for Cellulosic Biofuel Production. ADVANCES IN BIOENERGY 2017. [DOI: 10.1016/bs.aibe.2017.01.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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18
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Chundawat SPS, Paavola CD, Raman B, Nouailler M, Chan SL, Mielenz JR, Receveur-Brechot V, Trent JD, Dale BE. Saccharification of thermochemically pretreated cellulosic biomass using native and engineered cellulosomal enzyme systems. REACT CHEM ENG 2016. [DOI: 10.1039/c6re00172f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Tethering hydrolytic enzymes (e.g., cellulases) to protein scaffolds enhances biomass saccharification to sugars.
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Affiliation(s)
- Shishir P. S. Chundawat
- Department of Chemical & Biochemical Engineering
- The State University of New Jersey
- Piscataway
- USA
- DOE Great Lakes Bioenergy Research Center (GLBRC)
| | | | - Babu Raman
- Biosciences Division and BioEnergy Science Center
- Oak Ridge National Laboratory
- Oak Ridge
- USA
| | - Matthieu Nouailler
- LISM-UMR 7255 Institut De Microbiologie De La Mediterranee
- CNRS and Aix-Marseille University
- 13402 Marseille Cedex 20
- France
| | | | - Jonathan R. Mielenz
- Biosciences Division and BioEnergy Science Center
- Oak Ridge National Laboratory
- Oak Ridge
- USA
| | | | - Jonathan D. Trent
- Bioengineering Branch
- NASA Ames
- Moffett Field
- USA
- Biomolecular Engineering Department
| | - Bruce E. Dale
- DOE Great Lakes Bioenergy Research Center (GLBRC)
- Michigan State University
- East Lansing
- USA
- Chemical Engineering and Materials Science
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19
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Paulova L, Patakova P, Branska B, Rychtera M, Melzoch K. Lignocellulosic ethanol: Technology design and its impact on process efficiency. Biotechnol Adv 2015; 33:1091-107. [DOI: 10.1016/j.biotechadv.2014.12.002] [Citation(s) in RCA: 117] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 12/01/2014] [Accepted: 12/03/2014] [Indexed: 12/27/2022]
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20
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Kohn RA, Kim SW. Using the second law of thermodynamics for enrichment and isolation of microorganisms to produce fuel alcohols or hydrocarbons. J Theor Biol 2015; 382:356-62. [DOI: 10.1016/j.jtbi.2015.07.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2015] [Revised: 07/09/2015] [Accepted: 07/16/2015] [Indexed: 11/29/2022]
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21
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Pantazes RJ, Grisewood MJ, Li T, Gifford NP, Maranas CD. The Iterative Protein Redesign and Optimization (IPRO) suite of programs. J Comput Chem 2014; 36:251-63. [PMID: 25448866 DOI: 10.1002/jcc.23796] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 10/30/2014] [Accepted: 11/08/2014] [Indexed: 11/10/2022]
Abstract
Proteins are an important class of biomolecules with applications spanning across biotechnology and medicine. In many cases, native proteins must be redesigned to improve various performance metrics by changing their amino acid sequences. Algorithms can help sharpen protein library design by focusing the library on sequences that optimize computationally accessible proxies. The Iterative Protein Redesign and Optimization (IPRO) suite of programs offers an integrated environment for (1) altering protein binding affinity and specificity, (2) grafting a binding pocket into an existing protein scaffold, (3) predicting an antibody's tertiary structure based on its sequence, (4) enhancing enzymatic activity, and (5) assessing the structure and binding energetics for a specific mutant. This manuscript provides an overview of the methods involved in IPRO, input language terminology, algorithmic details, software implementation specifics and application highlights. IPRO can be downloaded at http://maranas.che.psu.edu.
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Affiliation(s)
- Robert J Pantazes
- Chemical Engineering Department, University of California, Santa Barbara, 3357 Engineering II, Santa Barbara, California, 93106
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22
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Thomas L, Joseph A, Gottumukkala LD. Xylanase and cellulase systems of Clostridium sp.: an insight on molecular approaches for strain improvement. BIORESOURCE TECHNOLOGY 2014; 158:343-50. [PMID: 24581864 DOI: 10.1016/j.biortech.2014.01.140] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 01/23/2014] [Accepted: 01/27/2014] [Indexed: 05/21/2023]
Abstract
Bioethanol and biobutanol hold great promise as alternative biofuels, especially for transport sector, because they can be produced from lignocellulosic agro-industrial residues. From techno-economic point of view, the bioprocess for biofuels production should involve minimal processing steps. Consolidated bioprocessing (CBP), which combines various processing steps such as pretreatment, hydrolysis and fermentation in a single bioreactor, could be of great relevance for the production of bioethanol and biobutanol or solvents (acetone, butanol, ethanol), employing clostridia. For CBP, Clostridium holds best promise because it possesses multi-enzyme system involving cellulosome and xylanosome, which comprise several enzymes such as cellulases and xylanases. The aim of this article was to review the recent developments on enzyme systems of clostridia, especially xylanase and cellulase with an effort to analyse the information available on molecular approaches for the improvement of strains with ultimate aim to improve the efficiencies of hydrolysis and fermentation.
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Affiliation(s)
- Leya Thomas
- Biotechnology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Trivandrum 695 019, India.
| | - Abhilash Joseph
- Department of Biotechnology & Microbiology, Kannur University, Thalassery Campus, Kannur 670 661, India
| | - Lalitha Devi Gottumukkala
- Biotechnology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Trivandrum 695 019, India
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Prawitwong P, Waeonukul R, Tachaapaikoon C, Pason P, Ratanakhanokchai K, Deng L, Sermsathanaswadi J, Septiningrum K, Mori Y, Kosugi A. Direct glucose production from lignocellulose using Clostridium thermocellum cultures supplemented with a thermostable β-glucosidase. BIOTECHNOLOGY FOR BIOFUELS 2013; 6:184. [PMID: 24359557 PMCID: PMC3878107 DOI: 10.1186/1754-6834-6-184] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Accepted: 12/05/2013] [Indexed: 05/04/2023]
Abstract
BACKGROUND Cellulases continue to be one of the major costs associated with the lignocellulose hydrolysis process. Clostridium thermocellum is an anaerobic, thermophilic, cellulolytic bacterium that produces cellulosomes capable of efficiently degrading plant cell walls. The end-product cellobiose, however, inhibits degradation. To maximize the cellulolytic ability of C. thermocellum, it is important to eliminate this end-product inhibition. RESULTS This work describes a system for biological saccharification that leads to glucose production following hydrolysis of lignocellulosic biomass. C. thermocellum cultures supplemented with thermostable beta-glucosidases make up this system. This approach does not require any supplementation with cellulases and hemicellulases. When C. thermocellum strain S14 was cultured with a Thermoanaerobacter brockii beta-glucosidase (CglT with activity 30 U/g cellulose) in medium containing 100 g/L cellulose (617 mM initial glucose equivalents), we observed not only high degradation of cellulose, but also accumulation of 426 mM glucose in the culture broth. In contrast, cultures without CglT, or with less thermostable beta-glucosidases, did not efficiently hydrolyze cellulose and accumulated high levels of glucose. Glucose production required a cellulose load of over 10 g/L. When alkali-pretreated rice straw containing 100 g/L glucan was used as the lignocellulosic biomass, approximately 72% of the glucan was saccharified, and glucose accumulated to 446 mM in the culture broth. The hydrolysate slurry containing glucose was directly fermented to 694 mM ethanol by addition of Saccharomyces cerevisiae, giving an 85% theoretical yield without any inhibition. CONCLUSIONS Our process is the first instance of biological saccharification with exclusive production and accumulation of glucose from lignocellulosic biomass. The key to its success was the use of C. thermocellum supplemented with a thermostable beta-glucosidase and cultured under a high cellulose load. We named this approach biological simultaneous enzyme production and saccharification (BSES). BSES may resolve a significant barrier to economical production by providing a platform for production of fermentable sugars with reduced enzyme amounts.
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Affiliation(s)
- Panida Prawitwong
- Biological Resources and Post-harvest Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba, Ibaraki 305-8686, Japan
| | - Rattiya Waeonukul
- Pilot Plant Development and Training Institute (PDTI), King Mongkut’s University of Technology Thonburi (KMUTT), Bangkok, Thailand
| | - Chakrit Tachaapaikoon
- Pilot Plant Development and Training Institute (PDTI), King Mongkut’s University of Technology Thonburi (KMUTT), Bangkok, Thailand
| | - Patthra Pason
- Pilot Plant Development and Training Institute (PDTI), King Mongkut’s University of Technology Thonburi (KMUTT), Bangkok, Thailand
| | - Khanok Ratanakhanokchai
- School of Bioresources and Technology, King Mongkut’s University of Technology Thonburi (KMUTT), Bangkok, Thailand
| | - Lan Deng
- Biological Resources and Post-harvest Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba, Ibaraki 305-8686, Japan
| | - Junjarus Sermsathanaswadi
- School of Bioresources and Technology, King Mongkut’s University of Technology Thonburi (KMUTT), Bangkok, Thailand
| | - Krisna Septiningrum
- Biological Resources and Post-harvest Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba, Ibaraki 305-8686, Japan
- University of Tsukuba Graduate School of Life and Environmental Sciences, 1-1-1 Ten-noudai, Tsukuba, Ibaraki 305-8572, Japan
| | - Yutaka Mori
- Biological Resources and Post-harvest Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba, Ibaraki 305-8686, Japan
| | - Akihiko Kosugi
- Biological Resources and Post-harvest Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba, Ibaraki 305-8686, Japan
- University of Tsukuba Graduate School of Life and Environmental Sciences, 1-1-1 Ten-noudai, Tsukuba, Ibaraki 305-8572, Japan
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Lin L, Xu J. Dissecting and engineering metabolic and regulatory networks of thermophilic bacteria for biofuel production. Biotechnol Adv 2013; 31:827-37. [DOI: 10.1016/j.biotechadv.2013.03.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 03/06/2013] [Accepted: 03/10/2013] [Indexed: 01/08/2023]
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25
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Grisewood MJ, Gifford NP, Pantazes RJ, Li Y, Cirino PC, Janik MJ, Maranas CD. OptZyme: computational enzyme redesign using transition state analogues. PLoS One 2013; 8:e75358. [PMID: 24116038 PMCID: PMC3792102 DOI: 10.1371/journal.pone.0075358] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 08/11/2013] [Indexed: 11/18/2022] Open
Abstract
OptZyme is a new computational procedure for designing improved enzymatic activity (i.e., kcat or kcat/KM) with a novel substrate. The key concept is to use transition state analogue compounds, which are known for many reactions, as proxies for the typically unknown transition state structures. Mutations that minimize the interaction energy of the enzyme with its transition state analogue, rather than with its substrate, are identified that lower the transition state formation energy barrier. Using Escherichia coli β-glucuronidase as a benchmark system, we confirm that KM correlates (R(2) = 0.960) with the computed interaction energy between the enzyme and the para-nitrophenyl- β, D-glucuronide substrate, kcat/KM correlates (R(2) = 0.864) with the interaction energy of the transition state analogue, 1,5-glucarolactone, and kcat correlates (R(2) = 0.854) with a weighted combination of interaction energies with the substrate and transition state analogue. OptZyme is subsequently used to identify mutants with improved KM, kcat, and kcat/KM for a new substrate, para-nitrophenyl- β, D-galactoside. Differences between the three libraries reveal structural differences that underpin improving KM, kcat, or kcat/KM. Mutants predicted to enhance the activity for para-nitrophenyl- β, D-galactoside directly or indirectly create hydrogen bonds with the altered sugar ring conformation or its substituents, namely H162S, L361G, W549R, and N550S.
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Affiliation(s)
- Matthew J. Grisewood
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Nathanael P. Gifford
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Robert J. Pantazes
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Ye Li
- Department of Chemical and Biomolecular Engineering, The University of Houston, Houston, Texas, United States of America
| | - Patrick C. Cirino
- Department of Chemical and Biomolecular Engineering, The University of Houston, Houston, Texas, United States of America
| | - Michael J. Janik
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Costas D. Maranas
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- * E-mail:
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Xu C, Huang R, Teng L, Wang D, Hemme CL, Borovok I, He Q, Lamed R, Bayer EA, Zhou J, Xu J. Structure and regulation of the cellulose degradome in Clostridium cellulolyticum. BIOTECHNOLOGY FOR BIOFUELS 2013; 6:73. [PMID: 23657055 PMCID: PMC3656788 DOI: 10.1186/1754-6834-6-73] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2013] [Accepted: 05/01/2013] [Indexed: 05/20/2023]
Abstract
BACKGROUND Many bacteria efficiently degrade lignocellulose yet the underpinning genome-wide metabolic and regulatory networks remain elusive. Here we revealed the "cellulose degradome" for the model mesophilic cellulolytic bacterium Clostridium cellulolyticum ATCC 35319, via an integrated analysis of its complete genome, its transcriptomes under glucose, xylose, cellobiose, cellulose, xylan or corn stover and its extracellular proteomes under glucose, cellobiose or cellulose. RESULTS Proteins for core metabolic functions, environment sensing, gene regulation and polysaccharide metabolism were enriched in the cellulose degradome. Analysis of differentially expressed genes revealed a "core" set of 48 CAZymes required for degrading cellulose-containing substrates as well as an "accessory" set of 76 CAZymes required for specific non-cellulose substrates. Gene co-expression analysis suggested that Carbon Catabolite Repression (CCR) related regulators sense intracellular glycolytic intermediates and control the core CAZymes that mainly include cellulosomal components, whereas 11 sets of Two-Component Systems (TCSs) respond to availability of extracellular soluble sugars and respectively regulate most of the accessory CAZymes and associated transporters. Surprisingly, under glucose alone, the core cellulases were highly expressed at both transcript and protein levels. Furthermore, glucose enhanced cellulolysis in a dose-dependent manner, via inducing cellulase transcription at low concentrations. CONCLUSION A molecular model of cellulose degradome in C. cellulolyticum (Ccel) was proposed, which revealed the substrate-specificity of CAZymes and the transcriptional regulation of core cellulases by CCR where the glucose acts as a CCR inhibitor instead of a trigger. These features represent a distinct environment-sensing strategy for competing while collaborating for cellulose utilization, which can be exploited for process and genetic engineering of microbial cellulolysis.
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Affiliation(s)
- Chenggang Xu
- BioEnergy Genome Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China
| | - Ranran Huang
- BioEnergy Genome Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China
| | - Lin Teng
- BioEnergy Genome Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China
| | - Dongmei Wang
- BioEnergy Genome Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China
| | - Christopher L Hemme
- Institute for Environmental Genomics, Department of Botany and Microbiology, University of Oklahoma, Norman, OK 73072, USA
| | - Ilya Borovok
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Qiang He
- Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, TN 37996, USA
| | - Raphael Lamed
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Edward A Bayer
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Jizhong Zhou
- Institute for Environmental Genomics, Department of Botany and Microbiology, University of Oklahoma, Norman, OK 73072, USA
| | - Jian Xu
- BioEnergy Genome Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China
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Verbeke TJ, Zhang X, Henrissat B, Spicer V, Rydzak T, Krokhin OV, Fristensky B, Levin DB, Sparling R. Genomic evaluation of Thermoanaerobacter spp. for the construction of designer co-cultures to improve lignocellulosic biofuel production. PLoS One 2013; 8:e59362. [PMID: 23555660 PMCID: PMC3608648 DOI: 10.1371/journal.pone.0059362] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 02/13/2013] [Indexed: 02/07/2023] Open
Abstract
The microbial production of ethanol from lignocellulosic biomass is a multi-component process that involves biomass hydrolysis, carbohydrate transport and utilization, and finally, the production of ethanol. Strains of the genus Thermoanaerobacter have been studied for decades due to their innate abilities to produce comparatively high ethanol yields from hemicellulose constituent sugars. However, their inability to hydrolyze cellulose, limits their usefulness in lignocellulosic biofuel production. As such, co-culturing Thermoanaerobacter spp. with cellulolytic organisms is a plausible approach to improving lignocellulose conversion efficiencies and yields of biofuels. To evaluate native lignocellulosic ethanol production capacities relative to competing fermentative end-products, comparative genomic analysis of 11 sequenced Thermoanaerobacter strains, including a de novo genome, Thermoanaerobacter thermohydrosulfuricus WC1, was conducted. Analysis was specifically focused on the genomic potential for each strain to address all aspects of ethanol production mentioned through a consolidated bioprocessing approach. Whole genome functional annotation analysis identified three distinct clades within the genus. The genomes of Clade 1 strains encode the fewest extracellular carbohydrate active enzymes and also show the least diversity in terms of lignocellulose relevant carbohydrate utilization pathways. However, these same strains reportedly are capable of directing a higher proportion of their total carbon flux towards ethanol, rather than non-biofuel end-products, than other Thermoanaerobacter strains. Strains in Clade 2 show the greatest diversity in terms of lignocellulose hydrolysis and utilization, but proportionately produce more non-ethanol end-products than Clade 1 strains. Strains in Clade 3, in which T. thermohydrosulfuricus WC1 is included, show mid-range potential for lignocellulose hydrolysis and utilization, but also exhibit extensive divergence from both Clade 1 and Clade 2 strains in terms of cellular energetics. The potential implications regarding strain selection and suitability for industrial ethanol production through a consolidated bioprocessing co-culturing approach are examined throughout the manuscript.
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Affiliation(s)
- Tobin J. Verbeke
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Xiangli Zhang
- Department of Plant Science, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Bernard Henrissat
- Centre national de la recherche scientifique, Aix-Marseille Université, Marseille, France
| | - Vic Spicer
- Department of Physics & Astronomy, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Thomas Rydzak
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Oleg V. Krokhin
- Department of Internal Medicine & Manitoba Centre for Proteomics and Systems Biology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Brian Fristensky
- Department of Plant Science, University of Manitoba, Winnipeg, Manitoba, Canada
| | - David B. Levin
- Biosystems Engineering, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Richard Sparling
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
- * E-mail:
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Ronan P, Yeung CW, Schellenberg J, Sparling R, Wolfaardt GM, Hausner M. A versatile and robust aerotolerant microbial community capable of cellulosic ethanol production. BIORESOURCE TECHNOLOGY 2013; 129:156-163. [PMID: 23238345 DOI: 10.1016/j.biortech.2012.10.164] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 10/30/2012] [Accepted: 10/31/2012] [Indexed: 06/01/2023]
Abstract
The use of microbial communities in the conversion of cellulosic materials to bio-ethanol has the potential to improve the economic competitiveness of this biofuel and subsequently lessen our dependency on fossil fuel-based energy sources. Interactions between functionally different microbial groups within a community can expand habitat range, including the creation of anaerobic microenvironments. Currently, research focussing on exploring the nature of the interactions occurring during cellulose degradation and ethanol production within mixed microbial communities has been limited. The aim of this study was to enrich and characterize a cellulolytic bacterial community, and determine if ethanol is a major soluble end-product. Cellulolytic activity by the community was observed in both non-reduced and pre-reduced media, with ethanol and acetate being major fermentation products. Similar results were obtained when sterile wastewater extract was provided as nutrient. Several community members showed high similarity to Clostridium species with overlapping metabolic capabilities, suggesting clostridial functional redundancy.
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Affiliation(s)
- Patrick Ronan
- Department of Chemistry and Biology, Ryerson University, Toronto, ON, Canada
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Mazzoli R. Development of microorganisms for cellulose-biofuel consolidated bioprocessings: metabolic engineers' tricks. Comput Struct Biotechnol J 2012; 3:e201210007. [PMID: 24688667 PMCID: PMC3962139 DOI: 10.5936/csbj.201210007] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2012] [Revised: 10/22/2012] [Accepted: 10/24/2012] [Indexed: 01/04/2023] Open
Abstract
Cellulose waste biomass is the most abundant and attractive substrate for "biorefinery strategies" that are aimed to produce high-value products (e.g. solvents, fuels, building blocks) by economically and environmentally sustainable fermentation processes. However, cellulose is highly recalcitrant to biodegradation and its conversion by biotechnological strategies currently requires economically inefficient multistep industrial processes. The need for dedicated cellulase production continues to be a major constraint to cost-effective processing of cellulosic biomass. Research efforts have been aimed at developing recombinant microorganisms with suitable characteristics for single step biomass fermentation (consolidated bioprocessing, CBP). Two paradigms have been applied for such, so far unsuccessful, attempts: a) "native cellulolytic strategies", aimed at conferring high-value product properties to natural cellulolytic microorganisms; b) "recombinant cellulolytic strategies", aimed to confer cellulolytic ability to microorganisms exhibiting high product yields and titers. By starting from the description of natural enzyme systems for plant biomass degradation and natural metabolic pathways for some of the most valuable product (i.e. butanol, ethanol, and hydrogen) biosynthesis, this review describes state-of-the-art bottlenecks and solutions for the development of recombinant microbial strains for cellulosic biofuel CBP by metabolic engineering. Complexed cellulases (i.e. cellulosomes) benefit from stronger proximity effects and show enhanced synergy on insoluble substrates (i.e. crystalline cellulose) with respect to free enzymes. For this reason, special attention was held on strategies involving cellulosome/designer cellulosome-bearing recombinant microorganisms.
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Affiliation(s)
- Roberto Mazzoli
- Department of Life Sciences and Systems Biology, University of Torino, Via Accademia Albertina 13, 10123 Torino, Italy
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30
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Hasunuma T, Kondo A. Development of yeast cell factories for consolidated bioprocessing of lignocellulose to bioethanol through cell surface engineering. Biotechnol Adv 2011; 30:1207-18. [PMID: 22085593 DOI: 10.1016/j.biotechadv.2011.10.011] [Citation(s) in RCA: 132] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2011] [Revised: 10/12/2011] [Accepted: 10/30/2011] [Indexed: 10/15/2022]
Abstract
To build an energy and material secure future, a next generation of renewable fuels produced from lignocellulosic biomass is required. Although lignocellulosic biomass, which represents an abundant, inexpensive and renewable source for bioethanol production, is of great interest as a feedstock, the complicated ethanol production processes involved make the cost of producing bioethanol from it higher compared to corn starch and cane juice. Therefore, consolidated bioprocessing (CBP), which combines enzyme production, saccharification and fermentation in a single step, has gained increased recognition as a potential bioethanol production system. CBP requires a highly engineered microorganism developed for several different process-specific characteristics. The dominant strategy for engineering a CBP biocatalyst is to express multiple components of a cellulolytic system from either fungi or bacteria in the yeast Saccharomyces cerevisiae. The development of recombinant yeast strains displaying cellulases and hemicellulases on the cell surface represents significant progress toward realization of CBP. Regardless of the process used for biomass hydrolysis, CBP-enabling microorganisms encounter a variety of toxic compounds produced during biomass pretreatment that inhibit microbial growth and ethanol yield. Systems biology approaches including disruptome screening, transcriptomics, and metabolomics have been recently exploited to gain insight into the molecular and genetic traits involved in tolerance and adaptation to the fermentation inhibitors. In this review, we focus on recent advances in development of yeast strains with both the ability to directly convert lignocellulosic material to ethanol and tolerance in the harsh environments containing toxic compounds in the presence of ethanol.
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Affiliation(s)
- Tomohisa Hasunuma
- Organization of Advanced Science and Technology, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
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31
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Li P, Zhu M. A consolidated bio-processing of ethanol from cassava pulp accompanied by hydrogen production. BIORESOURCE TECHNOLOGY 2011; 102:10471-10479. [PMID: 21962537 DOI: 10.1016/j.biortech.2011.08.134] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Revised: 08/26/2011] [Accepted: 08/31/2011] [Indexed: 05/31/2023]
Abstract
A biphasic fermentation approach was undertaken for the production of ethanol and hydrogen from cassava pulp. The glucose generated by co-culture of Clostridium thermocellum and Thermoanaerobacterium aotearoense was 13.65±0.45 g L(-1), which was 1.75 and 1.17-fold greater than that produced by mono-cultures of C. thermocellum and T. aotearoense, respectively. The accumulated glucose could be utilised rapidly by subsequently inoculated Saccharomyces cerevisiae. An inoculum ratio of 1:1, a thermophilic fermentation of 84 h, and a pulp concentration of 4% proved optimal for ethanol production, fermentation efficiency, and productivity. With these conditions, the ethanol level reached 8.83±0.31 g L(-1) with a fermentation efficiency of 64.95±2.71%. Hydrogen production of 4.06 mmol by the co-culture system was 1.54 and 2.09-fold greater than that produced by mono-cultures of C. thermocellum and T. aotearoense, respectively. This sequential co-culture approach provided a consolidated bio-processing means to produce ethanol and hydrogen from cassava pulp.
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Affiliation(s)
- Ping Li
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou Higher Education Mega Centre, Panyu, Guangzhou 510006, People's Republic of China
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Lin L, Song H, Tu Q, Qin Y, Zhou A, Liu W, He Z, Zhou J, Xu J. The Thermoanaerobacter glycobiome reveals mechanisms of pentose and hexose co-utilization in bacteria. PLoS Genet 2011; 7:e1002318. [PMID: 22022280 PMCID: PMC3192829 DOI: 10.1371/journal.pgen.1002318] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2011] [Accepted: 08/07/2011] [Indexed: 11/18/2022] Open
Abstract
Thermoanaerobic bacteria are of interest in cellulosic-biofuel production, due to their simultaneous pentose and hexose utilization (co-utilization) and thermophilic nature. In this study, we experimentally reconstructed the structure and dynamics of the first genome-wide carbon utilization network of thermoanaerobes. The network uncovers numerous novel pathways and identifies previously unrecognized but crucial pathway interactions and the associated key junctions. First, glucose, xylose, fructose, and cellobiose catabolism are each featured in distinct functional modules; the transport systems of hexose and pentose are apparently both regulated by transcriptional antiterminators of the BglG family, which is consistent with pentose and hexose co-utilization. Second, glucose and xylose modules cooperate in that the activity of the former promotes the activity of the latter via activating xylose transport and catabolism, while xylose delays cell lysis by sustaining coenzyme and ion metabolism. Third, the vitamin B12 pathway appears to promote ethanologenesis through ethanolamine and 1, 2-propanediol, while the arginine deiminase pathway probably contributes to cell survival in stationary phase. Moreover, by experimentally validating the distinct yet collaborative nature of glucose and xylose catabolism, we demonstrated that these novel network-derived features can be rationally exploited for product-yield enhancement via optimized timing and balanced loading of the carbon supply in a substrate-specific manner. Thus, this thermoanaerobic glycobiome reveals novel genetic features in carbon catabolism that may have immediate industrial implications and provides novel strategies and targets for fermentation and genome engineering. Renewable liquid fuels derived from lignocellulosic biomass could alleviate global energy shortage and climate change. Cellulose and hemicellulose are the main components of lignocellulosic biomass. Therefore, the ability to simultaneously utilize pentose and hexose (i.e., co-utilization) has been a crucial challenge for industrial microbes producing lignocellulosic biofuels. Certain thermoanaerobic bacteria demonstrate this unusual talent, but the genetic foundation and molecular mechanism of this process remain unknown. In this study, we reconstructed the structure and dynamics of the first genome-wide carbon utilization network of thermoanaerobes. This transcriptome-based co-expression network reveals that glucose, xylose, fructose, and cellobiose catabolism are each featured on distinct functional modules. Furthermore, the dynamics of the network suggests a distinct yet collaborative nature between glucose and xylose catabolism. In addition, we experimentally demonstrated that these novel network-derived features can be rationally exploited for product-yield enhancement via optimized timing and balanced loading of the carbon supply in a substrate-specific manner. Thus, the newly discovered modular and precisely regulated network elucidates unique features of thermoanaerobic glycobiomes and reveals novel perturbation strategies and targets for the enhanced thermophilic production of lignocellulosic biofuels.
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Affiliation(s)
- Lu Lin
- CAS Key Laboratory of Biofuels, Shandong Key Laboratory of Energy Genetics and BioEnergy Genome Center, Qingdao Institute of BioEnergy and BioProcess Technology, Chinese Academy of Sciences, Qingdao, China
- Institute for Environmental Genomics and Department of Botany and Microbiology, University of Oklahoma, Norman, Oklahoma, United States of America
| | - Houhui Song
- CAS Key Laboratory of Biofuels, Shandong Key Laboratory of Energy Genetics and BioEnergy Genome Center, Qingdao Institute of BioEnergy and BioProcess Technology, Chinese Academy of Sciences, Qingdao, China
| | - Qichao Tu
- Institute for Environmental Genomics and Department of Botany and Microbiology, University of Oklahoma, Norman, Oklahoma, United States of America
| | - Yujia Qin
- Institute for Environmental Genomics and Department of Botany and Microbiology, University of Oklahoma, Norman, Oklahoma, United States of America
| | - Aifen Zhou
- Institute for Environmental Genomics and Department of Botany and Microbiology, University of Oklahoma, Norman, Oklahoma, United States of America
| | - Wenbin Liu
- Institute for Environmental Genomics and Department of Botany and Microbiology, University of Oklahoma, Norman, Oklahoma, United States of America
| | - Zhili He
- Institute for Environmental Genomics and Department of Botany and Microbiology, University of Oklahoma, Norman, Oklahoma, United States of America
| | - Jizhong Zhou
- Institute for Environmental Genomics and Department of Botany and Microbiology, University of Oklahoma, Norman, Oklahoma, United States of America
- * E-mail: (JZ); (JX)
| | - Jian Xu
- CAS Key Laboratory of Biofuels, Shandong Key Laboratory of Energy Genetics and BioEnergy Genome Center, Qingdao Institute of BioEnergy and BioProcess Technology, Chinese Academy of Sciences, Qingdao, China
- * E-mail: (JZ); (JX)
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Chandel AK, Chandrasekhar G, Silva MB, Silvério da Silva S. The realm of cellulases in biorefinery development. Crit Rev Biotechnol 2011; 32:187-202. [DOI: 10.3109/07388551.2011.595385] [Citation(s) in RCA: 145] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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34
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Shao X, Jin M, Guseva A, Liu C, Balan V, Hogsett D, Dale BE, Lynd L. Conversion for Avicel and AFEX pretreated corn stover by Clostridium thermocellum and simultaneous saccharification and fermentation: insights into microbial conversion of pretreated cellulosic biomass. BIORESOURCE TECHNOLOGY 2011; 102:8040-5. [PMID: 21683579 DOI: 10.1016/j.biortech.2011.05.021] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Revised: 05/06/2011] [Accepted: 05/08/2011] [Indexed: 05/02/2023]
Abstract
In this study, efforts were taken to compare solubilization of Avicel and AFEX pretreated corn stover (AFEX CS) by SSF and Clostridium thermocellum fermentation, with an aim to gain insights into microbial conversion of pretreated cellulosic biomass. Solubilization rates for AFEX CS are comparable for the two systems while solubilization of Avicel is much faster by C. thermocellum. Initial catalyst loading impacts final cellulose conversion for SSF but not for C. thermocellum. Hydrolysis of the two substrates using cell-free C. thermocellum fermentation broth revealed much smaller difference in cellulose conversion than the difference observed for growing cultures. Tests on hemicellulose removal and particle size reduction for AFEX CS indicated that substrate accessibility is very important for enhanced solubilization by C. thermocellum.
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Affiliation(s)
- Xiongjun Shao
- Thayer School of Engineering at Dartmouth College, 8000 Cummings Hall, Hanover, NH 03755, USA
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35
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Metabolic engineering of Clostridium cellulolyticum for production of isobutanol from cellulose. Appl Environ Microbiol 2011; 77:2727-33. [PMID: 21378054 DOI: 10.1128/aem.02454-10] [Citation(s) in RCA: 153] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Producing biofuels directly from cellulose, known as consolidated bioprocessing, is believed to reduce costs substantially compared to a process in which cellulose degradation and fermentation to fuel are accomplished in separate steps. Here we present a metabolic engineering example for the development of a Clostridium cellulolyticum strain for isobutanol synthesis directly from cellulose. This strategy exploits the host's natural cellulolytic activity and the amino acid biosynthesis pathway and diverts its 2-keto acid intermediates toward alcohol synthesis. Specifically, we have demonstrated the first production of isobutanol to approximately 660 mg/liter from crystalline cellulose by using this microorganism.
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